Eccentrically disposed male and female spline teeth

ABSTRACT

Eccentrically disposed male and female spline teeth having unlike contact engagement therebetween from one succeeding set of teeth to the next and like contact engagement therebetween only once per revolution.

United @iates Ptet EQCENTRHCALLY DHSPOSED ME AND FEMALE SPLKNE TEE [72]inventor: George V. 11 1 22077 W.

Lake Road, Rocky River, Ohio 44116 [22] Filed: Feb. 8, 1971 [21]Appl.No.: 113,136

{52] US. Cl ..418/61, 64/9 R, 64/31 [51] int. C1. ..F16d 3/04, F16d3/18, F03c 3/00 [58] Field of Search ..4l8/61; 64/9 R, 31; 74/804,

[56] References (Iited UNITED STATES PATENTS 11/1965 Huber 418/6 1 5]Sept, w, 1972 3 ,258,994 7/ 1 966 Gorfin .74/ 8 04 3,288,034 11/1966White et a1. ..418/6l 3,549,285 12/ 1970 Woodling ..4l8/6l 1,799,348 4/1931 Apple ..74/804 Primary Examiner-Carlton R. Croyle AssistantExaminer-John J. Vrablik Attorney-Woodling, Krost, Granger & RustEccentrically disposed male and female spline teeth having unlikecontact engagement therebetween from one succeeding set of teeth to thenext and like contact engagement therebetween only once per revolution.

12 wing figures PATENTED SEP 19 I972 INVENTOR. GEORGE V. WOODLI N6ECCENTRICALLY DISPOSED MALE AND FEMALE SPLINE TEETH BACKGROUND OF THEINVENTION The mating female and male spline teeth at the opposite endsof a wobble shaft which interconnects an orbiting fluid rotor and arotatable valve, in a fluid pressure device, are subject to wear due tothe fact that the reversal of the spheroidal rubbing action between themating spline teeth always occurs at the same place, cycle after cycle.The wear may be considered in term-s of molecular fatigue, resultingfrom the reversal of the rubbing action occurring at the same locationat the end of each orbital cycle. Where one end of the wobble shaft ispivoted about a fixed point, as is the case in the prior art, the sameset of male and female molecules contact each other, at the point of thereversal, six times per revolution of the wobble shaft. The molecularfatigue may be likened to that of bending the free end of a wire at thesame spot to break it off as compared to bending it over a distributedsection where it takes longer to break it off.

In this invention, the fatigue of the spline teeth is distributed,whereby the same set of male and female molecules do not contact eachother at the same place at the end of each reversal of the rubbingaction, but contact each other only once per revolution of the wobbleshaft, as compared to six times per revolution as is the case in theprior art.

Accordingly, it is an object of my invention to shift the location ofthe fatigue of the spline teeth at the end of each reversal of therubbing action over a distributed area.

Another object is to distribute the wear between the mating female andmale spline teeth, whereby the same set of male and female molecules donot contact each other at the same place at the end of each reversal ofthe spheroidal rubbing action, but contact each other only once perrevolution of the wobble shaft, as compared to six times per revolution,as is the case in prior art.

Another object is to provide an eccentric pivot for one end of thewobble shaft instead of a fixed pivot.

Another object is the provision of eccentrically disposed male andfemale spline teeth having unlike contact engagement therebetween fromone succeeding set of teeth to the next and like contact engagementtherebetween only once per revolution.

Another object is to limit the extent that the male and female matingspline teeth may move in an axial direction relative to each other.

SUMMARY OF THE INVENTION The invention constitutes eccentricallydisposed male and female spline teeth having unlike contact engagementtherebetween from one succeeding set of teeth to the next and likecontact engagement therebetween only once per revolution.

Other objects and a fuller understanding of this invention may be had byreferring to the following description and claims, taken in conjunctionwith the accompanying drawings, in which:

FIG. 1 is an elongated, partial sectional view of a fluid pressuredevice embodying the features of my invention;

FIG. 2 is a representation of a male shank provided on the terminal endportion of a hollow shaft adapted to fit within a female socket of arotary valve;

FIG. 3 is a view taken along the line 3-3 of FIG. 1, under the end cap,showing the stator-rotor mechanism;

FIG. 4 is a cross sectional view of the main shaft and the wobble shaftonly taken along the line 4-4 of FIG. I, the view illustrating the factthat the female spline teeth are eccentrically disposed with referenceto the axis of the main shaft;

FIG. 5 is a view similar to FIG. 4, but illustrating the fact that themale spline teeth are eccentrically disposed with reference to the axisof the wobble shaft;

FIG. 6 is an illustration showing the condition where the left-hand endof the wobble shaft is pivoted about a fixed axis, as is the case in theprior art, wherein it is noted that the same angulated position of thewobble shaft repeats itself at the end of each cycle;

FIGS. 7 to 12 are views similar to FIG. 6, but show the condition wherethe left-hand end of the wobble shaft is eccentrically pivoted about theaxis of the main shaft, wherein it is noted that the same angulatedposition of the wobble shaft is not repeated until the wobble shaftmakes one complete revolution which comprises six orbital cycles.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to the drawing,the fluid pressure device in which my invention may be incorporated,comprises generally a hollow housing 20 having substantially a squarecross-section. A mounting flange or end plate 21 may be secured to theleft-hand end of the housing. Intermediate the ends of the hollowhousing 20, there is provided an annular internal rim 22 which generallyseparates the hollow housing into a left-hand end compartment and aright-hand end compartment. Rotatively mounted in the left-hand endcompartment is a main shaft 25 having a fixed axis 69 substantiallycoinciding with the longitudinal axis of the fluid pressure device. Abushing 27 and a rotary valve 28 are mounted in the right-hand endcompartment. On the right-hand end of the hollow housing, there ismounted a square stationary valve member 29 by means of suitable screws30. The rotary valve 28 is adapted to be rotated relative to thestationary valve member 29 for controlling the entrance of fluid to andthe exit of fluid from a stator-rotor mechanism 31 comprising a stator32 and a rotor 33. An end cap 34 encloses the statorrotor mechanism 33.The entrance of fluid to and the exit of fluid from the stator-rotormechanism flows through a plurality of fluid openings 40 in thestationary valve member 29 controlled by the rotation of the rotaryvalve 28. The stator-rotor mechanism 31 and the end cap 34 are securedto the stationary valve member 29 by means of screws 35. Fluid isdelivered to and from the housing 20 through a pair of fluid ports 23and 24. An orbital or wobble shaft 36 interconnects the main shaft 25with the rotor 33 of the stator-rotor mechanism 31 and is adapted totransmit torque therebetween.

The main shaft 25 comprises an enlarged internal portion having areduced external portion 41 extending axially outwardly of the hollowhousing 20 through the mounting flange 21. The enlarged internal portionof the main shaft is supported preferably by tapered roller bearings,generally indicated by the reference character 42. A tightening nut 54which threadably engages male threads 55 secures the bearings 42 againstaxial movement upon the main shaft.

The tapered bearings constitute common bearing means for the main shaftand the rotary valve, and thus the main shaft and the rotary valve aredisposed for rotation about the same fixed axis 69. The common bearingmeans directly support the main shaft 25 and indirectly support therotary valve 28 through extension drive means comprising a hollow shaft44 integrally connected to the main shaft. The hollow shaft 44 extendsinto the right-hand compartment and supportingly rotates the rotaryvalve 28 relative to the sta tionary valve member 29. The hollow shaft44 terminates in a male shank 45 which slidably fits within a femalesocket provided in the rotary valve 28. This connection comprises anon-rotatable connection and rotates the rotary valve upon rotation bythe main shaft.

Although not limited thereto, the stator 32 has seven internal teeth andthe rotor 33 has six external teeth. The interrneshing teeth uponrelative movement therebetween define operating fluid chambers. Therotor has an axis 70 which orbits about a fixed axis 69 of the stator,being the same fixed axis about which the main shaft and the rotaryvalve rotate. The rotor also rotates about its own axis. The orbitalshaft 36, which interconnects the rotor 33 and the main shaft 25 isdisposed to drive the rotary valve 28 relative to the stationary valvemember. The right-hand end of the orbital shaft 36 has an operativeconnection with the rotor 33 and comprises male spline teeth 71 fittingwithin female spline teeth 72 of the rotor. The left-hand end of theorbital shaft 36 has an operative connection with the main shaft 25 andcomprises male spline teeth 73 fitting within female spline teeth 74 inthe main shaft. As illustrated in FIG. 4, the female spline teeth 74have a center 53 which is eccentrically disposed with reference to thefixed axis 69. The eccentricity need be only a small amount, sufficientto cause a mismatching of the molecules and may reside in a rangevarying from approximately percent to 50 percent of the eccentricity ofthe rotor 33. Thus, the left-hand end of the orbital shaft 36 isdisposed for eccentric movements about the fixed axis 69, while theright-hand end is disposed for both orbital and rotational movements,partaking that of the orbital and rotational movements of the rotor 33.

The stationary valve member 29 has first and second side wall means 38and 39, with the first side wall means 38 held in facing relationship tothe inside face of the stator-rotor mechanism. The second side wallmeans 39 defines a reference plane against which the rotary valvesealingly engages. The reference plane is also identified by the samenumber as that for the second side wall means. Extending through thestationary valve member 29, is a shaft opening 52. The orbital shaft 36extends through the shaft opening 52 and has a shaft axis 51 defining anorbit angle with respect to the fixed axis 69. The right-hand end of theshaft axis 51 meets with the rotor axis.70, and partakes of the samemovement. The orbital shaft 36 makes a rotational movement about its ownshaft axis 51 and an orbital movement about the fixed axis 69.

The stationary valve member 29 in FIG. 1 shows an inclined stop-limitsurface 47 extending outwardly of the shaft opening 52. Extendingoutwardly of the orbital shaft 36, is a shoulder 48 which has a flat,inclined limit surface 49 disposed to abuttably engage the stoplimitsurface 47 to limit relative axial movement between the male and femalespline teeth. Accordingly, the male and female spline teeth 73 and 74are kept in full axial engagement with each other.

Since the stator 32 has seven internal teeth and the rotor 33 has sixexternal teeth, the rotor 33 orbits six times about the fixed axis 69for each rotation of the wobble shaft 36 about its own axis 51. Thus, inFIG. 6, where the left-hand end of the wobble shaft is illustrated asbeing pivoted about the fixed axis 69, as is the case in the prior art,it is to be observed that the same angulated position of the wobbleshaft repeats itself at the end of each cycle, which is six times perrevolution of the wobble shaft, as represented by the six black dots 75.The circle 44 in FIG. 6 represents the hollow shaft 44 whichsupportingly rotates the rotary valve 28. The intervals between thesix-black-dots represent the amount that the rotary valve rotates pereach orbital cycle. In FIG. 6, the reversal of the spheroidal rubbingaction of the male and female spline teeth occurs at the same locationat the end of each orbital cycle, because the angulated position of thewobble shaft repeats itself at the end of each cycle. Thus, the same setof male and female molecules are fatigued six times per revolution ofthe rotary valve 23.

FIGS. 7 to 12 illustrate the situation in my invention, where the sameset of male and female molecules are fatigued only once for eachrevolution of the rotary valve 28, which means that the fatigue at thesame spot has been reduced by one-sixth. FIG. 7 shows the angulatedposition of the wobble shaft at the start of the first orbit, where theblack-dot 75, representing the position of the rotary valve 28, is atzero degrees with respect to the vertical. FIG. 8 shows the angulatedposition of the wobble shaft at the start of the second orbit, where theblack-dot 75, representing the position of the rotary valve 28, is at 60with respect to the vertical in a clockwise direction, which rotation isopposite in direction to that of the orbit movement.

FIGS. 9 to 12 progressively show the augulated position of the wobbleshaft at the start of each succeeding cycle, where it is noted that theaugulated position of the wobble shaft does not repeat itself until therotary valve makes one complete revolution, being at the startingposition as shown in H6. 7.

The action above described illustrates the fact that the reversal of thespheroidal rubbing of the male and female spline teeth repeats itselfonly once per revolution of the wobble shaft or rotary valve, instead ofsix times, as is the case in the prior art. The fatigue is thusdistributed, which means that the wear qualities of the male and femalespline teeth are improved. It is also to be observed that, since thewobble shaft is limited against axial movement to the right, the contactengagement of the male and female spline teeth, so far as axial contactis concerned, repeats itself only once per revoliition of the rotaryvalve. Thus, the male and female spline teeth, so far as the axialmismatching of the molecules is concerned, have a small amount ofrelative axial movement therebetween, which repeats itself only once perrevolution. The axial mis-matching also improves the wear qualities.

Although this invention has been described in its preferred form with acertain degree of particularity, it is understood that the presentdisclosure of the preferred form has been made only by way of exampleand that numerous changes in the details of construction and thecombination and arrangement of parts may be resorted to withoutdeparting from the spirit and the scope of the invention as hereinafterclaimed.

What is claimed is:

1. A torque transmitting device, including rotor means having a rotoraxis and rotatable means having a fixed axis, shaft means operativelyinterconnecting said rotor means and said rotatable means, said rotormeans having a combined movement comprising an orbital movement aboutsaid fixed axis and a rotational movement about its own axis, saidorbital movement being at a first speed about said fixed axis and saidrotational movement being at a second speed about said rotor axis, saidshaft having a shaft axis and first and second shaft portions axiallyspaced apart from each other along said shaft axis, said first shaftportion being operatively connected to and having a combined movementpartaking that of said rotor means, said second shaft portion beingoperatively connected to said rotatable means for orbital movementrelative to said fixed axis, said rotor means having first female splineteeth therein encircling said rotor axis, said first shaft portionhaving first male spline teeth thereon encircling said shaft axis, saidfirst female spline teeth and said first male spline teeth being of thesame number, all of said first male spline teeth respectively fittingwithin and respectively making contact with all' of said first femalespline teeth to provide a rotational shaft speed the same as said secondspeed of said rotor means, said rotatable means having second femalespline teeth therein encircling said fixed axis, said second shaftportion having second male spline teeth thereon encircling said shaftaxis, said second female spline teeth and said second male spline teethbeing of the same number, all of said second male spline teethrespectively fitting within and respectively making contact with all ofsaid second female spline teeth, said second female spline teetheccentrically encircling said fixed axis for orbiting said second shaftportion about said fixed axis at said second speed.

2. The structure of claim 1, wherein said second speed is slower thansaid first speed.

3. The structure of claim 1, wherein said rotatable means includes valvemeans.

4. The structure of claim 1, wherein said male and female spline teethhave substantially spheroidal contact engagement therebetween.

5. The structure of claim 1, having axis limit means to limit the extentthat said male and female spline teeth may axially move relative to eachother.

1. A torque transmitting device, including rotor means having a rotoraxis and rotatable means having a fixed axis, shaft means operativelyinterconnecting said rotor means and said rotatable means, said rotormeans having a combined movement comprising an orbital movement aboutsaid fixed axis and a rotational movement about its own axis, saidorbital movement being at a first speed about said fixed axis and saidrotational movement being at a second speed about said rotor axis, saidshaft having a shaft axis and first and second shaft portions axiallyspaced apart from each other along said shaft axis, said first shaftportion being operatively connected to and having a combined movementpartaking that of said rotor means, said second shaft portion beingoperatively connected to said rotatable means for orbital movementrelative to said fixed axis, said rotor means having first female splineteeth therein encircling said rotor axis, said first shaft portionhaving first male spline teeth thereon encircling said shaft axis, saidfirst female spline teeth and said first male spline teeth being of thesame number, all of said first male spline teeth respectively fittingwithin and respectively making contact with all of said first femalespline teeth to provide a rotational shaft speed the same as said secondspeed of said rotor means, said rotatable means having second femalesplIne teeth therein encircling said fixed axis, said second shaftportion having second male spline teeth thereon encircling said shaftaxis, said second female spline teeth and said second male spline teethbeing of the same number, all of said second male spline teethrespectively fitting within and respectively making contact with all ofsaid second female spline teeth, said second female spline teetheccentrically encircling said fixed axis for orbiting said second shaftportion about said fixed axis at said second speed.
 2. The structure ofclaim 1, wherein said second speed is slower than said first speed. 3.The structure of claim 1, wherein said rotatable means includes valvemeans.
 4. The structure of claim 1, wherein said male and female splineteeth have substantially spheroidal contact engagement therebetween. 5.The structure of claim 1, having axis limit means to limit the extentthat said male and female spline teeth may axially move relative to eachother.